Igntion system for internal combustion engine



March 29, 1966 J. COUFAL 3,242,916

IGNITION SYSTEM FOR INTERNAL COMBUSTION ENGINE Filed Aug. 29, 1963 5 Sheets-Sheet 1 l6l T I62 lo 27 28 ll 2. I v. ia

INVENTOR /0/n Z 0 0727/ March 29, 1966 J. COUFAL 3,242,916

IGNITION SYSTEM FOR INTERNAL COMBUSTION ENGINE Filed Aug. 29, 1963 5 Sheets-Sheet 2 INVENTOR. ./an 50 ufa/ J. COUFAL March 29, 1966 IGNITION SYSTEM FOR INTERNAL COMBUSTION ENGINE 5 Sheets-Sheet 5 Filed Aug. 29, 1965 INVEN TOR. /7 faufa/ BY WM m March 29, 1966 couF 3,242,916

IGNITION SYSTEM FOR INTERNAL COMBUSTION ENGINE Filed Aug. 29, 1963 5 Sheets-Sheet 4.

INVENTOR. [47/7 Koo/b/ BY MM/Q March 29, 1966 J, cou 3,242,916

IGNITION SYSTEM FOR INTERNAL COMBUSTION ENGINE Filed Aug. 29, 1963 5 SheetsSheet 5 I L l I l a i I P36 1 l IN VENTOR.

.75? faufa/ mu/m United States Patent 3,242,916 IGNITION SYSTEM FOR INTERNAL COMBUSTION ENGINE Jan Coufal, Kromeriz, Czechoslovakia, assignor to Pal- Magneton, narodni podnik, Kromeriz, Czechoslovakia Filed Aug. 29, 1963, Ser. No. 305,364 Claims priority, application Czechoslovakia, Sept. 4, 1962, 5,104/62 7 Claims. (Cl. 123-148) This invention relates to ignition systems for internal combustion engines, and particularly to a system for energizing spark plugs in a multi-cylinder engine.

In its more specific aspects the invention is concerned with a spark ignition system which avoids the use of a distributor and associated problems. Transistor circuits have heretofore been employed in ignition systems to overcome the difficulties inherent in the mechanically moved contacts of more conventional distributors, but the known transistor ignition systems have been rather complex and costly.

An object of this invention is the provision of a simple ignition system without distributor which is adaptable to exacting requirements, and whose timing can be made very precise.

The invention contemplate the use of two power circuits each of which includes the primary winding of a transformer and a switch means capable of assuming a conductive and a non-conductive condition, and conductively connected to a source of electric current for passage of current from the source through the associated transformer winding in the conductive condition of the switch means. Switch actuating means are connected to a source of a sequence of electric timing pulses and the switch means of each power circuit for putting one of the switch means into its conductive condition and the other switch means into the non-conductive condition in response to a first pulse of the sequence, and for reversing the con-ditions of the switch means in response to a second timing pulse of the sequence. The secondary windings of the transformers are respectively connected to spark plugs.

The exact nature of this invention as well as other objects and advantages thereof will be readily apparent from consideration of the following specification relating to the annexed drawing in which:

FIG. 1 is the circuit diagram of an ignition system according to this invention for a four-cylinder internal combustion engine;

FIG. 2 shows a modification of the circuit of FIG. 1;

FIG. 3 is the circuit diagram of an ignition circuit for an eight-cylinder engine;

FIG. 4 shows the arrangement of the cylinders in the engine connected to the ignition system of FIG. 3 in con ventional representation;

FIG. 5 is a valve timing diagram for the engine of FIG. 4; and

FIG. 6 is the circuit diagram of an ignition system of the invention for a six-cylinder engine.

Referring now to the drawing in detail, and initially to FIG. 1, there is shown the wiring diagram of an ignition system having two power circuits. A P-N-P transistor 10 and a step-up transformer 12 are the principal elements of the first power circuit, and a P-N-P transistor 11 and step-up transformer 13 in the second circuit. The primary windings 22, 18 of the transformers 12, 13, and current limiting resistors 21, 19 are respectively arranged in series between the collectors of the transistors and the negative terminal of a direct current source.

The base of the transistor 10 is connected to the collector of the transistor 11 through a resistor 14 and the base of the transistor 11 is connected to the negative 3,242,916 Patented Mar. 29, 1966 terminal of the current source through a resistor 15 and a timing switch 16 whose contacts are alternatingly opened and closed by a rotating cam 161 having two lobes and mounted on a drive shaft 162.

The emitters of the transistors are connected by a common biasing resistor 17 to the positive terminal of the current source. This arrangement permits current flow through the resistor 11 and the primary winding 18 of the transformer 13 when the switch 16 is closed, whereas current flow through the transistor 10 is practically zero because the voltage between the emitter and collector of the transistor 11 is insignificant, the base of the transistor 10 being connected to the collector of the transistor 11 through the resistor 14.

When the switch 16 is opened, the transistor 11 blocks current fiow to the primary winding 18 of transformer 13, and the magnetic field of the primary winding is rapidly reduced to zero, thereby producing a current pulse in the secondary winding 20. Because of the increased potential at the collector of the transistor 11, the transistor 11 simultaneously permits current flow through the primary winding 22 of the transformer 12 within the limits set by the resistor 21, and a magnetic field is induced in the winding 22 of the transformer 12. When the switch 16 is again closed, the magnetic field of the winding 22 collapses, and a current pulse is induced in the winding 23.

v A resistor 24 interposed between the negative terminal of the current source and the emitters of both transistors 10, 11 is selected in such a manner that a suitable positive potential is applied to the bases of the transistors 10, 11 from the positive terminal of the source through respective resistors 25, 26. Capacitors 27, 28 are arranged -in parallel with the resistors 25, 26 to control the instantaneous base potential when the conductivity of the transistors changes.

The spark plugs of two cylinders V V of a four cylinder engine are connected to the secondary winding 23 of the transformer 12 in the first power circuit, and the spark plugs of the other two cylinders V V; are connected to the secondary winding 20 of the transformer 13, in the second power circuit. The firing order of the cylinders is 1342. Their operation during two crankshaft revolutions in indicated in the following table.

P1511011 V V2 V V4 stroke Expansi0n Exhaust Compression Intake.

Exhaust Intake 1. Expansion Compression. Intake Compression. Exhaust Expansion. Compression Expansion Intake Exhaust.

If the firing order is 1432 or 1-2-3-4, the spark plugs of the cylinders V and V are connected with one power circuit, and those of the cylinders V and V with the other power circuit. The illustrated connection is also employed for the firing order 1-2-3-4. 1

The ignition system shown in FIG. 1 is operated follows:

At the moment at which the switch 16 opens, sparks are produced in the cylinders V and V Assuming that ignition is timed to occur several degrees ahead of the TDC (top dead center) position of the piston in the cylinder, the spark in the cylinder V passes through a spent fuel mixture since the inlet valve opens approximately at 13 ahead of TDC, as is conventional. There The cam 161 is connected to the camshaft of the enginev in such a manner that the switch 16 is closed again after the camshaft turns 90. Sparks are generated hereby in the cylinders V and V and ignition takes place in the cylinder V only for the reasons set forth above. The further ignition cycle will be evident from the above table.

The ignition system shown in FIG. 1 generates a spark alternatingly in the two power circuits upon closing and opening of the timing switch 16. The switch may be driven by the illustrated cam having two lobes and driven by the camshaft or by a single lobe cam driven by the crankshaft. The ignition system does not rely for operativeness on a critical cam configuration. The engine revolutions at which oscillations set in at the switch are much higher than at the contact of a conventional ignition system, and the ignition system is capable of operating at higher engine speed and higher engine output than an otherwise comparable conventional system.

Only a control or timing current flows through the switch 16, and the power circuit for the spark current is switched by the transistors 10, 11. Sparks are generated upon opening and closing of the switch 16 at 90 intervals if the switch cam 161 is coupled to the camshaft, or at 180 intervals, if the cam is coupled to the crankshaft.

The ignition system illustrated in FIG. 2 is similar to that shown in FIG. 1 and operates basically in the same manner. It does not rely on a switch even for opening and closing a control or timing circuit. The elements of the ignition system of FIG. 1 other than the switch 16 are again employed in the ignition system of FIG. 2, and are shown within a chain-dotted rectangular frame 37. They are identified by the same reference numerals as in FIG. 1 and Will not be described again.

The system of FIG. 2 employs as a source of timing signals an;oscillator whose main elements are an N-P-N' transistor 29 and a transformer 30. The primary winding 31 of the transformer is arranged in series between the collector of the transistor and the positive terminal of the direct current source, and the secondary winding 32 of the transformer 30 is arranged in feed-back circuit connecting the transistor base to the negative source terminal. The frequency of oscillation is determined by the inductivity of the primary winding 31 and the capacity of a capacitor 33 arranged in parallel circuit with the winding 31.

A resistor 34 connects the base of the transistor 29 to the positive source terminal to provide positive bias voltage, and a capacitor 35 in the feedback circuit blocks the flow of direct current into the latter circuit. The oscillations produced are rectified by a rectifier 36, and the rectified output of the oscillator is employed to switch the power circuits.

The rectifier output is controlled by a timing disk 38 which is composed by two quadrants 381 of metallic material and two non-metallic quadrants which sequentially pass the transformer 30 during rotation of the disc 382. The disk is coupled to the engine cam shaft in a manner not further illustrated, and, may be replaced by a disk consisting ,of one metallic 180 sector and a similar nonmetallic sector, and coupled to the crankshaft. The parameters of the oscillator circuit are selected in such a manner as to permit oscillation when one type of quadrant is aligned with the transformer 30, and to suppress oscillations when the other type of quadrant is near the transformer. The non-metallic quadrants may be constituted by cut-outs.

Current thus flows through the recifier 36 to the switching circuits in pulses whose timing is controlled by the rotation of the disk 38. Flow of current from the positive terminal of the direct current source to the base of the transistor 11 is prevented by the rectifier 36 during the periods in which the oscillator is inoperative.

The precise ignition timing is determined by the angular position of the transformer 30 relative to the axis of the. disk 38, and therefore relative to the TDC position of each piston. Spark advance may be controlled automatically in response to engine load by a diagrammatically illustrated linkage 39 which is connected by a spring and a pull rod actuated by the vacuum in the intake manifold, and shifts the transformer 30 as indicated by the double arrow. Spark advance in response to engine speed is achieved by turning the disk 33 relative to the driving camshaft by means of a centrifugal governor.

FIG. 3 shows an ignition system of the invention for an eight-cylinder internal combustion engine. The ignition system illustrated is intended for the Tatra, type 603, eight-cylinder engine whose firing order is 1-3-5-2-7- 845, whose cylinders are arranged in two banks of four at right angles to each other, and whose crankshaft has four cranks that are offset The manner in which the eight pistons are connected to the four cranks of the engine is evident from FIG. 4 in which the pistons are labelled V to V The valve diagram in FIG. 5 shows the condition of the eight cylinders during two revolutions (720) of the crankshaft. The four phases of the engine cycle are indicated in FIG. 5 by capital letters. S is intake, K is compression, E is expansion, and V is exhaust.

The engine cycle illustrated in FIG. 5 permits the spark plugs of cylinders V V V and V to be connected to one power circuit, and these of cylinder V V V and V to be connected to the other power circuit shown in FIG. 3 as will be described in more detail hereinafter. If the firing order were l-625 8-3-7-4, the spark plugs in one power circuit would be V V V V and those in the other circuit would be V V V and V A firing order 1273684-5 would call for connecting V V V and V to one circuit, and V V V V to the other circuit.

Ignition occurs in cylinder V near the end of compression stroke K at 8 before the TDC position of the piston. A spark is simultaneously generated in the cylinder V whose intake valve opens approximately 15 before TDC, and whose exhaust valve is open until approximately 20 after TDC. There is nothing in the cylinder V that could be ignited.

Sparks are simultaneously also generated in cylinders V and V As is seen in FIG. 5, the cylinder V is at the end of its expansion phase and its exhaust valve is already open, opening of the valve being timed at 50 before BDC (bottom dead center). The cylinder V is at the end of its intake stroke S. Since the intake valve remains open until 55 after BDC, compression has not started yet. Neither the cylinder V nor the cylinder V contains anexplosive mixture at the time of ignition in the cylinder V It has been found that the position of the crankshaft is not proportional to the amount of fuel mixture drawn into the cylinder. The fuel mixture does not ingite until it is compressed to a certain minimum pressure, the limiting pressure decreasing with the intensity of the spark. Both last-mentioned factors militate against ignition in cylinder V under the conditions shown in FIG. 5 at the moment discussed.

When the contents of cylinder V are ignited next near the end of the compression phase K in that cylinder, the simultaneously produced sparks in the cylinders V V and V do not cause ignition, and no sparks are generated in the other four cylinders. It is readily apparent from FIG. 5, that all eight cylinders fire in the desired order at intervals of 90 of crankshaft portion.

The ignition system illustrated in FIG. 3 which operates an eight-cylinder engine in the manner described above is basically closely similar to that shown in FIG. 2, and therefore also to that illustrated in FIG. 1, provisions for the greater number of cylinders being made by use of additional transformers and of a modified timing circuit.

The diagram of FIG. 3 shows two power circuits respectively employing P-N-P transistors 40, 41. The primary windings 56, 57 of two step-up transformers 42, 43

and a current limiting resistor 44 are arranged in series in the collector circuit of the transistor 40 which leads to the negative terminal of a source of direct current. The primary windings 52, 53 of two transformers 45, 46 and a current limiting resistor 47 are similarly arranged in the collector circuit of the transistor 41. The emitters of the transistors 40, 41 are connected to each other and to a bias resistor 48 which links them to the positive terminal of the direct current source. The elements described so far constitute the two power circuits which energize the eight spark plugs connected in pairs to the secondarywindings 58, 59, 54, 55 of the transformers 42, 43, 45, 46.

The base of the transistor 40 is connected through a resistor 49 to the collector of the transistor 41, and the base of the latter is connected through a resistor 56 and rectifier 51 to a control oscillator, the power circuit of the transistor 41 being open to the flow of current as long as the oscillator generates alternating current by oscillating. Flowing current includes magnetic fields about theprimary windings 52, 53. Upon interruption of that current, as described hereinabove with reference to FIG. 1, the transistor 40 controlling the other power circuit becomesconductive in an analogous manner, not requiring further description.

A resistor 60 interposed between the negative terminal of the direct current source and the emitters of the two ransistors 40, 41, resistors 61, 62, respectively arranged between the bases of the transistors 40, 41' and the positive terminal of the current source, and capacitors 63, 64 arranged in parallel circuit with the resistors 61, 62 are the equivalents'of the corresponding elements 24 and 28 in the ignition system of FIG. 1.

A timing signal is delivered to the transistors 40, 41 by an oscillator whose basic element is an N-P-N transistor 65, and whose oscillating circuit consists of a capacitor 66 and a coil 67 arranged in parallel circuit between the positive terminal of the principal current source and the collector of the transistor 65. The parameters of the capacitor 66 and the coil 67 determine the oscillator frequency.

The collector of the transistor 65 is connected to the emitter by a capacitor 68, and the emitter is connected to the negative terminal of the principal power source by a capacitor 69, the capacitors 68, 69 forming a capacitative divider for supplying feedback to the emitter. Two resistors 70, 71 arranged in series to form a voltage divider connected to collector of the transistor 65 to the negative terminal of the current source. A tap between the rsistors 70, 71 is connected to the transistor base to provide bias voltage. Capacitors 72, 73 respectively connect the negative terminal of the source to the aforementioned tap and the positive terminal to allow passage of alternating current. A resistor 74 connecting the emitter of the transistor 65 to the negative terminal of the current source stabilizes the working point of the transistor. v

A timing or control signal is drawn from the oscillator circuit by the rectifier 51 at the emitter of the transistor 65, but may also be taken from a tap of the coil 67.

A timing disk 75 is rotatably mounted close to the coil 67. It difiers from the disk 38 shown in FIG. 2 by being composed of 'four metallic and four non-metallic sectors, each sector extending over 45, and is connected to camshaft of the engine in a manner not further shown. Because of the influence of the disk 75 on the parameters of the oscillating circuit 66, 67, the oscillator operates intermittently, and current passes through the rectifier 51 in control pulses each of which has a duration corresponding to a 45 rotation of the disk and is separated from the next pulse by a period of oscillator inoperativeness of equal duration.

Spark timing is achieved as described hereinabove with reference to FIG. 2. Primary spark advance is controlled by the position of the coil 67 relative to the disk 75, andto the TDC positions of the pistons. Automatic timing control in response to engine load is obtained by a link 76 conventionally shown in FIG. 3, and connected to a diaphragm actuated by the vacuum in the intake manifold. A centrifugal governor, not itself shown, may be employed in a basically conventional manner for shifting the angular position'of the disk 75 relative to the camshaft in order to make the ignition advance responsive to the instantaneous engine speed.

The power circuits illustrated in FIG. 3 can be controlled by a cam-operated single switch in the manner evident from FIG. 1, and a cam having four lobes may be employed instead of the eight lobe cam used in conventional distributors.

FIG. 6 shows an ignition system of the invention for a six-cylinder internal combustion engine. Its power circuits 78 differ from those shown in FIG. 3 only by connections between one terminal of each of the secondary windings 55, 59 and a terminal of the corresponding primary windings 53, 57. The oscillator circuit 77 which provides control pulses through a rectifier 36 is identical with that shown in FIG. 2 except for a timing disk 79 which cooperates with the transformer 30 and in which 60 sectors of metallic and non-metallic material alternate in a circumferential direction. The disk 79 is coupled to the camshaft of the non-illustrated six-cylinder engine. It Will be appreciated that the oscillator arrangement may be replaced by .a switch operated by a three-lobed cam in the manner shown in FIG. 1.

An engine having a firing order 15362-4 and a crankshaft equipped with six cranks offset from each other can be operated by the ignition system illustrated in FIG. 6 with the spark plugs of the cylinders V V and V connected to one power circuit, and the remaining spark plugs connected to the other circuit in a manner obvious from the preceding descriptions of the operation and fourand eight-cylinder engines, and from FIG. 5.

The ignition system of the invention is thus readily adapted to engines having any desired number of cylinders. It can be simply modified for engines having even more cylinders than eight by inserting additional transformers into the collector leads of the transistors in the power circuits. The advantages of the ignition systems of the invention over conventional systems increase with the number of cylinders because of the complexity of rotary ignition distributor arrangements which increases with an increasing number of cylinders.

The invention is not limited to the specific circuits illustrated and described. The N-P-N transistors shown may be replaced by N-P-N transistors and vice versa, and those skilled in the art will have nodifficulty in suitably modifying other circuit "features for this purpose. Either terminal of the principal current source may be grounded as desired, and as consistent with the circuit employed. The transistors may be replaced by other semi-conductor elements or by electronic tubes having characteristics consistent with the described functions.

It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

What I claim is:

1. An ignition system for an internal combustion engine comprising, in combination (a) a source of electric current;

(b) two power circuits connected to said source, each circuit including (1) a primary winding, and

(2) switch means having a conductive and a nonconductive condition and being conductively connected to said source and to said winding for serial passage of current from said source through said winding and said switch means in said conductive condition of said switch means;

(c) a source of a sequence of electric triming pulses;

((1) switch actuating means connected to said source of timing pulses and to only a single selected one of said switch means of said power circuits.

(1) coupling circuitry connecting said selected one of said switch meansto the switch means of the other power circuit in a dependent mutual coupling manner,

(2) means for biasing. said selected switch means to its nonconductive condition in the. absence of the application thereto of a timing pulse,

(3) so that the energization of the selected switch means in response to the application thereto of a single timing pulse is effective to simultaneously de-energize the switch means of said other power circuit and so that the de-energization of the selected switch means in response to. the absence of the application thereto of a timing pulse. is effective to. energize the switch means of said other power circuit,

(e) two secondary windings inductively coupled to said primary windings respectively and constituting respective transformers therein; and

(f) a spark plug in circuit with each secondary wind- 2. An ignition system as set forth in claim 1, wherein each switch means includes a transistor having three electrodes, .a first electrode being conductively connected to said source, and a second electrode being conductively connected to the associated primary winding; said. switch actuating means including a resistor conductively interposed between the third electrode of one of said transistors and the second electrode of the other transistor; and said source of timing pulses being connected to the third electrode of' said other transistor.

3. An ignition system as set forth in claim 1, wherein said engine has a camshaft and a crankshaft, andsaid source of pulses. includes pulse generating means, and motion transmitting means for connecting pulse said gener- 8 ating means to one of said shafts for synchronizing the timing of said pulses to the movement of said one shaft.

4. An ignition system as set forth in claim 3, wherein said pulse generating means include a switch and a source of electric current in circuit with said switch, the starting and the interruption of said current by said switch constituting said pulses.

5. An ignition system as set forth in claim 3, wherein said pulse generating means include an oscillator and timing means movable for shifting said oscillator between an operative and an inoperative condition, said timing means being connected to said motion transmitting means for movement thereby.

, 6. An ignition system as set forth in claim 5, wherein said oscillator includes an oscillator circuit, and saidtiming means include means for cyclically varying a parameter of said oscillating circuit.

7. An ignition circuit as set forth in claim 6, wherein said oscillator circuit includes an inductor, and said means for varying said parameter include a metallic member and means for cyclically moving said metallicmember relative to said inductor.

References Cited by theiExaminer UNITED STATES PATENTS 1,050,162 1/1913 Nickel 123-148 1,335,933 4/1920 Bohli 123-148 2,002,114 5/1935 June 123148 3,035,108 5/1962 Kaehni 123-148 3,072,823 1/1963 Kirk 123-148 XR 3,087,001 4/1963 Short et al. ,l'23148 3,152,281 10/1964 Robbins 123 -148 XR MARK NEWMAN, Primary Examiner.

RICHARD B. WILKINSON, Examiner.

LAURENCE M. GOODRIDGE, Assistant Examiner. 

1. AN IGNITION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE COMPRISING, IN COMBINATION (A) A SOURCE OF ELECTRIC CURRENT; (B) TWO POWER CIRCUITS CONNECTED TO SAID SOURCE, EACH CIRCUIT INCLUDING (1) A PRIMARY WINDING, AND (2) SWITCH MEANS HAVING A CONDUCTIVE AND A NONCONDUCTIVE CONDITION AND BEING CONDUCTIVELY CONNECTED TO SAID SOURCE AND TO SAID WINDING FOR SERIAL PASSAGE OF CURRENT FROM SAID SOURCE THROUGH SAID WINDING AND SAID SWITCH MEANS IN SAID CONDUCTIVE CONDITION OF SAID SWITCH MEANS; (C) A SOURCE OF A SEQUENCE OF ELECTRIC TRIMING PULSES; (D) SWITCH ACTUATING MEANS CONNECTED TO SAID SOURCE OF TIMING PULSES AND TO ONLY A SINGLE SELECTED ONE OF SAID SWITCH MEANS OF SAID POWER CIRCUITS. (1) COUPLING CIRCUITRY CONNECTING SAID SELECTED ONE OF SAID SWITCH MEANS TO THE SWITCH MEANS OF THE OTHER POWER CIRCUIT IN A DEPENDENT MUTUAL COUPLING MANNER, (2) MEANS FOR BIASING SAID SELECTED SWITCH MEANS TO ITS NONCONDUCTIVE CONDITION IN THE ABSENCE OF THE APPLICATION THERETO OF A TIMING PULSE, (3) SO THAT THE ENERGIZATION OF THE SELECTED SWITCH MEANS IN RESPONSE TO THE APPLICATION THERETO OF A SINGLE TIMING PULSE IS EFFECTIVE TO SIMULTANEOUSLY DE-ENERGIZE THE SWITCH MEANS OF SAID OTHER POWER CIRCUIT AND SO THAT THE DE-ENERGIZATION OF THE SELECTED SWITCH MEANS IN RESPONSE TO THE ABSENCE OF THE APPLICATION THERETO OF A TIMING PULSE IS EFFECTIVE TO ENERGIZE THE SWITCH MEANS OF SAID OTHER POWER CIRCUIT, (E) TWO SECONDARY WINDINGS INDUCTIVELY COUPLED TO SAID PRIMARY WINDINGS RESPECTIVELY AND CONSTITUTING RESPECTIVE TRANSFORMERS THEREIN; AND (F) A SPARK PLUG IN CIRCUIT WITH EACH SECONDARY WINDING. 